The present invention relates to novel pigments which possess good adhesion and spreadability and have the effect of preventing or lessening that transmission of ultraviolet and infrared rays. Ultraviolet and infrared rays are known to cause erythematous response or skin pigmentation in mammals, e.g., humans.
It has been pointed out that when the skin is exposed to ultraviolet rays or infrared rays in the sunlight, skin temperature increases due to infrared rays, whereby the photochemical reaction of ultraviolet rays is accelerated so that so-called sunburn tends to be caused. Furthermore, near infrared rays at 760 nm to 1500 nm can be a factor causing low temperature burn or skin aging changes, accompanied by evaporation of epidermal moisture, so-called photoaging, etc. As cosmetics which have a light-protecting effect, there have been recently provided cosmetic compositions in which UV absorbents of an organic compound type such as quinine sulfate or p-aminobenzoic acid are incorporated or in which the effect of shielding ultraviolet rays at 300 to 400 nm is achieved by utilizing the light scattering effect of inorganic powders, for example, zinc oxide or titanium oxide.
In addition, as powders for simultaneously scattering ultraviolet rays and infrared rays, nylon particles having zirconium oxide bound thereto or aluminum powders treated with titanium oxide have been developed. However, these prior art cosmetics do not have good adhesion or spreadability on the skin and are also unsatisfactory in other desired properties such as smoothness, soft touch, transparency, color hue, etc. and in their ability to prevent transmission of both ultraviolet rays and infrared rays.
Furthermore, organic compounds that prevent transmission of substantial amounts of ultraviolet rays and infrared rays at the same time are unknown, and available compounds are irritating to the skin, and have insufficient stability to light. In particular, reflection of a sufficient amount of near infrared rays at 760 nm to 1500 nm is not achieved by the available organic compounds.
West German Patent No. 32210451A discloses a titanium oxide-covered mica-type pearlescent pigment; in preparing the pigment, a trace amount of zirconium oxide is deposited together with titanium oxide for purposes of improving its luminescence and adhesion of titanium oxide. However, the pigment does not have sufficient infrared ray reflection properties. Furthermore, the luminescence is so strong that it is unsuited as a powder foundation, etc. for use in cosmetics.
In addition, the infrared ray reflection properties of pearlescent pigments having a red interference color which is obtained by covering mica with 50 to 60 wt. % of titanium oxide is reported by Poelman et al. [M.C. Poelman et al., Preprints of the XIVth I.F.S. Congress Barcelona, Vol. II, 749 (1986)]. However, in this pigment in the luminescence is also strong so that the pigment is undesirable for use as a powder foundation.